Portable power-operated hammer



June 25, 1929. J HILSTAD 1,718,425

PORTABLE .POWER OPERATED HAMMER Filed May 9, 1927 2 Sheets-Sheet 1 I R 1 A mw m ATTORNEY June 25, 1929. J. R. HILSTAD PORTABLE POWER OPERATED HAMMER 2 Sheets-Sheet 2 Filed May 9, 1927 3 N. w s Q Q NW Wm v VIIIIII/ INVENTOR J0/1'N 77? ///4 07/917 ATTORNEY 50 the lines 22 Patented June 25 19 29.

UNITED STATES PATENT, OFFICE."

JOHN R. HILSTAD, OE WHITTIER, CALIFORNIA, ASSIGNOR F ONE-THIRD TO HARRY H. CANTERBURY AND TWO-THIRDS TO GEORGE G. GRIFFITH, BOTH '01 WHITTIEB,

, CALIFORNIA.

ZPOlBTAIBLE POWER-OPERATED HAMMER.

Application filed May 9, 1927. Serial No. 189,932.

My invention relates to portable power operated hammers of the character embodied in my co-pending application 40,964, filed July 1, 1925, which is capable of being manually moved over sheet metal work such as motor vehicle bodies and fenders and which operates to remove from the metal.un--

dulations of any configuration to. restore the metal to its original form.

It is a. purpose of'my present invention to v provide a power operated hammer having a different and superior means by which the intensity of the hammerin action in respect to the work can be manua ly controlled in a manner to produce intermittent blows of any desired intensit so that the most delicate hammering of s eet metal or the most severe can be effected at the will of the operator.

It is also a purpose of my invention to provide a power operated hammer in which the hammer element thereof is active to reduce a hammering action only when the e ement is pressed into engagement with the work, the

element being normall inactive arid becom- 2 i'n'ginactive immediate y upon-removal thereof from the work, thus greatly reducing wear of the element and the adjacent parts of the hammer but permanently relieving the hand of the operator from the vibratory action of h the hammer when the element is not in actual use.

A further purpose of m'yinvention is the provision in a power operated hammer of means to permit the hammering element to be projected from itscasing sufficiently to free itself from the actuating mechanism rather than restrain the element to the extent of destroying the casing and probable injury to the operator when the element for any reason is thrown beyond its normal inward stroke.

I willdescribe only one form of portable power operated hammer embodying my invention,and will then point out the novel-features thereof in claims.

In the accompanying drawings,

Figure 1 is a view showing in vertical longitudinal section one form of hammer embodying my invention;

Figures 2 and 3 are sectional views taken on and 33,- respectively, of Figurel;

Serial No.

Figure 4 is a fragmentary sectional view taken on the line 1-4 of Figure 2;

F lgures 5 and 6 are sectional views taken on the lines 55 and 66, r espectively, of Figure Referring specifically to the drawings, my

invention,- in its present embodiment, is

shown as comprising a casing 15 of tubular form, to which is secured between its ends a tubular handle 16 adapted to be gripped in moving the hammer as a unit over a piece of work. Mounted for reciprocating movement within the casing 15 is a hammer element designated generally at E and comprising a shank 17 of one diameter, on the lower end of which is formed a head 18. On the upper end ofthe shank 17 is a body 19 constructed to provide a right-angled shoulder or abutment 20 on the lower face of which a cam 21 is adapted to ride. The upper portion of the shank 17 is cut out to accommodate the cam 21 in the reciprocating movement of the hammer element. Above the body 19 the hammer element is provided with a shank 22 slightly reduced in diameter in respect to the body and provided at its upper end with a reduced portion 23 terminating in a head 24. These elements work in a cap 25 removably fitted on the upper end of the casing 15 and secured against displacement by means of a pin 26 engaged by a resilient arm 27 secured by a screw 28 to the casing. This arm 27 is bendable outwardly to disengage the pin 26 and thereby permit removal of the cap. The upper end of the ca is formed .with an inturned Ii 25 provi ed for the purpose of retaining t ereon a closure disk 29 provided with a vent opening 30; This disk may be formed of metal or any other suitable material capable of being readily fractured to allow the projection of the upper end of the hammer element through the top of the cap 25. Should the hammer, element for any reason be projected in its upward stroke above its normal extreme elevated position, the disk 29 will yield to permit the projection of the head 24 therethrough rather than confine the hammer element within the cap and thus injure the cap. It will be understood that the disk 29 can be readily replaced with a new one should it become fractured. V a

To retain the hammer element against accidental displacement from the casing and yet permit of the required reciprocating movement thereof, a washer 31 is mounted on the reduced portion 23 of the hammer element so as to abut a shoulder 32 provided at the junction of the cap and casing and to thus define the lowermost position of the hammer element. This washer 31 is of such internal diameter as to readily pass over the head 24, but it is locked against displacement by means of a U-shaped key 33 applied to the reduced portion 23 so as to be interposed between the head 24 and the washer 31. This key can be readily removed to permit subsequent removal of the washer 31 by first removing the cap 25. h

On the lower end of the casing 15 is threaded a collar 34, and on the outer surface of the collar at diametrically opposed points are two pockets 34 (Figure 6). These pockets receive balls 36 which work in vertical grooves 37 of a chp-shaped anvil 38: The lower ends of the grooves 37 communicate with an annu lar groove 39, formed in the anvil 38, the grooves 37 functioning as entrances for the balls so that the latter will be finally received in the groove 39 and thereby permit a 90 movement of theanvil to displace the balls from the vertical grooves 37 and thereby secure the balls against displacement. A pair of ears 40 are formed on the casing 15, and secured between these cars by means of a cotter pin 41 is a locking pin 42 which extends downwardly within one of the grooves 37, thereby locking the anvil 38' against rotative movement on the collar 34. i V

From the foregoing described mounting of the anvil 38, it will be clear that the anvil is capable of vertical movement on' the casing 15 in order that itfinay respond to various adjustments in stroke 'of the hammer element E, as will be described hereinafter. I

Within the casing 15 and surrounding the, shank 17 .is acup shaped housing 43 for, a coiled expansiblegspring 44 interposed between the housing and the hammer head 18. The housing is provided with a radially extending'lug 45 movable in a slot 46 of the easing and engageable by one end of a lever 47 fulcrumed on cars 48 formed on the handle 16 at the points indicated at 49. The opposite end of the lever 47 is curved in the form of a trigger to facilitate operation of the lever. by the index fin er of the hand when the latter is gripped a out the handle 16. Operation of the lever 47 depresses the lug 45 and,

hence, the housing 43 .to compress the spring 44 and thus increase its normal tension. In this manner the intensity of the blows produced bv the hammer element can'be increased from a minimum as will behereinafter described.

The cam 21 :is formed on one end of a shaft 50 journaled in ball bearings 51 and 52 fitted in the handle, as shown in Figure 1, with the shaft provided with flanges 53 to secure the shaft against longitudinal displacement.

The rear end of the handle 1.6 is constructed to accommodate a pinion 54 keyed to the shaft 50 and constantly meshing with a smaller pinion 55 secured to or formed integral with the inner end of astub shaft 56. A cover plate 57 is removably secured to the free end of the handle 16an d this cover plate is pro vided with a tubular extension 58 containing liners 59 in which the stub shaft 56 is journaled. The stub shaft is provided with a pocket 60 in which is adapted to be received a flexible shaft (not shown) driven by a motor or other suitable means for rotating the stub shaft 56 and thereby effecting a driving of the" shaft 50 through the intermediate pinions 54 and 55. Pins 61 project-into the pocket 60 and may provide an operative "connection between the stub shaft and the flexible shaft inserted into the pocket.

The handle 16 is provided with a screw plug 62 which, when removed, will permit the injection into the handle of asuitable 'lubri- R cant. The handle is completely lilled with the lubricant so that it will be distributed to the bearings 51 and 52, as well as to the pinions 54 and 55, it being noted that the pinion 54 is A constructed withopenings 54 to allow the the passage of lubricant through the forward .1 it

ball bearing 51. As clearly shown in Figure 2, the upper edge of the anvil 38 is formed with an anular bead 64' which engages the lower end of a rod 65 movable in a bracket 66 on the casing 15. This rod extends upwardly and into the casing through a suitable opening 66 where its upper end engages the lower end of a latching pawl 67 pivoted on a pin 68 and engaged by a spring 69, so that it will be yieldably urgedinwardly to the solid line position shown." In this position of the pawl, it engages the shoulder or abutment 20 in order to hold the hammer element in an elevated or retracted position, and thus render the cam 21 inefi'ective to reciprocate the hammer element. However, by moving the anvil 38 upwardly to the dotted line position shown in Figure 2, an upward movement of the rod 65 is effected to force the pawl 67 to the dotted line position in which it is out of engagement with the shoulder 20, thereby. permitting the cam to effect the reciprocation of the hammer element. 1

The operation of the hammeris as fol- K lows With the pawl 67 engaging the shoulder 20, the cam 21, in its rotative movement by actuation of the shaft 50, does not engage the shoulder 20 and, hence,-the hammer element remains at a standstill. Upon applying the hammer to the work, the anvil 38 will be moved upwardly on the casing 15, thereby moving the pawl 67 free of the shoulder and thereby allowing the hammerelement to respond to the action of the spring 44. As soon as the hammer element is lowered, the cam, in its rotative movement, operates to elevate the element, and under the continued lowering of the hammer element by the spring and its subsequent elevation by the cam, a reciprocating motion is imparted'to the hammer element to cause an intermittent tapping of the head 18 against the anvil 38, thereby producing a hammering action upon the work. The construction of the cam 21 is such that, in its rotative movement it suddenly releases the hammer element following elevation thereof, so as to allow the spring 44, in its expansive movement, to project the element downwardly to produce the hammering action. The intensity of this hammering action can be varied at will through actuation of the lever 47. In the normal position of the lever the housing 43 occupies its uppermost position, in which the spring 44 is completelyexpanded. However, upon actuation of the lever, the housing is moved downwardly.

thereby increasing the normal tension of the spring and, as a consequence, increasing its expansive action on the hammer element when released by the cam 21. In this manner, the intensity of the hammering action of the element is increased,and it will be understood that the degree of increase can be varied in accordance with the downward adjustment of the housing 43. Upon release of the lever 47, the housing 43 is free to return to its nor mal elevated position under the action of the spring 44, so that the hammering element will operate with its normal hammering intensity.

As soon as the anvil is removed from the work, it returns to its lowermost position, thereby releasing the rodand permitting the pawl 67 under the action of the spring 6%) to, return to its normal position in which it, engages the shoulder 20 and thereby hold the hammering element against reciprocation. Thus, the hammering element is active only when the anvilais in actual engagement with the work. Obviously, this mode of operation greatly reduces wear of the hammering element and adjacent parts, and the amount'of the lower edge of the anvil is rounded as in vibration to which the hand is subjected when the hammering element is actually reciprocating.

By reference to Figures 1 and 2, it will be noted that the working surface of the anvil 38 indicated at 38 is of convex form, while dicated at 38". By constructing the anvil in this manner, it is possible to concentrate the pounding action of the hammer on a particular and relatively small spoton the work, as it will be understood that by the convexity of the surface 38? the center of'such surface alone can be brought intocontact with the work. The rounded edge 38 permits the anvil to be applied to normally inaccessible parts of a sheet metal surface, the hammer as a unit being positioned with respect to the i the anvil may be'somewhat loosely fitted on the collar 34, soas to allow limited lateral movement thereof, and the anvil shifting to this lateral position when applying the edge of the anvil to the work.

Although I have herein shown and described only one form 'ofporta'ble power operated hammer embodying my invention, it is to beunderstood thativarious changes and modifications may bemadethereinwithout departing from the spirit and scope of the appended claims. a r

I claim as my invention:

1. A power operated hammer comprising a reciprocable hammer element, means for actuatingthe hammer element, an anvil against which the hammer element J is' adapted to strike, said anvil being adjustable by compressing it against the work being hammered to vary in a limited degree the pounding action of the hammering element, a spring assojciated with the element to resist its movement ject the element toward the work, and man-V uall operable means for varying the tension of t e spring. 7,

2. A power operated hammer comprising a hammer element, means for yieldably urging' the element to one extreme position, power operated means for moving the element to another'extreme position in a manher; to place the first means under tension and then suddenly release the element, thereby allowing the first means to act expansively on the element, and means for ad usting the first means to vary its expansive action on the element comprising a housing movable to compress the first means, and a manually operable lever for moving the hous- A power operated hammer comprising a hammer element yieldably urged to one extreme position, means for moving the hammer element to another extreme position and releasing the same, means for holding the hammer element in the second mentioned position, and means operable upon application of the hammer element to a piece of work forv "a hammer element yieldably urged to one extreme position, means for moving the ham mer element to another extreme position and .,releasing the same, an anvil against which the hammer element is adapted to strike, said anvil eing supported for limlted movement,

hammer element is adapted to strike, said anvil being supported for limited movement, a spring-pressed pawl normally acting to hold the hammer element in the second extreme position, and a rod operable by the anvil for moving the pawl free of the hammer element.

6. A power operated hammer comprising a reciprocable hammer element, means for actuating the element, and a cap for the element having a displaceable portion so positioned as to be struck and displaced from the cap by the hammer element upon movement of the latter beyond a predetermined 'position. I

7. A power operated hammer comprisin a reciprocable hammer element, a housing or the element including'a cap, and a closure member removably fitted in the cap and so positioned as to be struck and displaced from the-cap by the hammer element should the latter move beyond a predetermined position.

8 A power operatedhammer, a reciprocable hammering element, a casing therefor, an anvil on thecasifl'g, non-friction means for supporting the anvil for movement lengthwise of the casing, and meansfor looking the anvil to the casing.

92 In a power operated hammer, a reciprocable hammer element having a head, a mem-- ber mounted and movable on the hammer element, a spring interposed between the member and the head, and manually operable "means en aging the member to move the latter where y the tension of said spring can be increased. J '10, A poweroperatedhammer comprisin a hammer element, an anvil against whic element, means associated with the element" the hammer element is adapted to strike, the anvil being adjustable by pressing it against the workbeing hammered'to vary in a limited degree the pounding action of the hammering for resisting its movement in a direction away from the workv and normally acting to project the element towards'the work, and manually 0 enable means for varying the degree of pro ecting action of the last means.

11. A power operated hammer comprising. a hammer element, means foryieldably urging the element to one extreme posltiom, power operated means for 'moving-the element to another extreme. position in a manner to place the first means under tension and ,then suddenly release the element, thereby ied in claim 1 wherein .the last means com-' prises an abutment movable to compress the spring, and a pivoted member for actuating the abutment.

13. A power operated hammer comprising a hammer-element,,resilient means correlated with the hammer element normally acting to urge the element to one positiom means for moving the hammer to 1 another position against the action of thefirst means, and means for adjusting the first means to vary the degree of urging action thereof against the hammer element, comprising an abutment movable to vary the tension of the resilient means, and a pivoted member for actuating the abutment.

14. A power operated hammer comprising a hammer element, resilient meanscorrelated with the hammer element normally acting to urge the element to one position,

means for moving the hammer to another position against the action of the first means,

and means for adjusting the first means to.

the head and member and having a portion thereof received in the latter, and manually operable means engaging the member for moving the latter to thereby vary the tension of said spring.

16. A power operated hammer comprising a hammer element normally urged to one position, means for moving the hammer element to another position and releasing it, an

anvil sup orted for limited movement and against w ich the hammer element is adapted to strike, means for holding the hammer element in the second mentioned position, and

means operable by movement of the anvil as when applying the hammer element to a piece of work for operating the holding means to release the hammer element.

'17. A power operated hammer comprising a casing, a hammer element reciprocable 'in the casing, a coil spring for urging the hammer element to one extreme position, means for moving the hammer element to its other extreme position and then suddenly'releasing the element, a, cup shaped housing movable inthe casing and receiving a portion of the "spring, the casing having a slot, and a manually operable lever for actuating the mer element to another extreme position and housing to compress the spring, mounted on releasing the same, mechanical means for 10 the casing and having a portion projecting holding the hammer element in the second through said slot and bearing against the mentioned position, and means operable 5 housing. upon application of the hammer element to 18. A power operated hammer comprisa piece of work for rendering said holding ing a hammer element yieldably urged to one means ineflective to hold the hammer element. extreme position, means for moving the ham- JOHN R. HILSTAD. 

